Lebl-Basic-Analysis-I · Problem 7.6.2

Metric Spaces

Mathematics · fixed-point-theorem

Problem

In the proof of Picard's theorem, show that if f:[−h,h]→Jf: [-h,h] \to J is continuous, then F(t,f(t))F\bigl(t,f(t)\bigr) is continuous on [−h,h][-h,h] as a function of tt. Use this to show that T(f)(x)≔y0+∫0xF(t,f(t)) dtT(f)(x) \coloneqq y_0 + \int_0^x F\bigl(t,f(t)\bigr)\,dt is well-defined and that T(f)∈C([−h,h],R)T(f) \in C\bigl([-h,h],\mathbb{R}\bigr).

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